Described below is a method for rolling a rolled stock produced in an ingot casting process, known as a slab or an ingot, in a rolling train, wherein, prior to being rolled, the rolled stock has the shape of a truncated pyramid with a base area, a top area and four side areas. Also described is a rolling train for rolling such a rolled stock, an open- and/or closed-loop device for such a rolling train, a machine-readable program code for an open- and/or closed-loop device of the kind, and a storage medium for a machine-readable program code of the kind.
With many rolled stocks it makes no sense economically to manufacture them as continuous casting products, since too few of the rolled stocks are used. Such a rolled stock is in that case produced e.g. in an ingot casting process and prior to the rolling operation is referred to as a “slab”. After rolling the slab forms a sheet or strip, ideally having a cuboidal shape. In ingot casting, an ingot mold is used which is implemented in a slightly conical shape, with its cross-section tapering downward. Because of the special shape of the ingot mold, the slab is detached completely from the ingot mold wall after solidifying when the slab is pressed out of the ingot mold by special tongs. Without the conicity or convergence of the ingot mold it would not be possible to release the slab from the mold. However, the slab takes on the shape of the ingot mold and subsequently there is the problem that the double conicity of the slab, i.e. a thickness wedge and a width wedge of the slab, must be removed during rolling.
A major problem in the rolling of slabs is to achieve a basic rectangular shape with a constant width over the length of the sheet or strip. Present-day practice in order to influence the width of the slab is to employ vertically aligned compression rollers which make the hot-rolled strip thicker in a longitudinal edge region and consequently can reduce the width of the strip in a certain area.
DE 196 13 718 C1 and DE 197 57 486 A1 each disclose a system for producing hot-rolled strip, wherein upstream of a first horizontal rolling stand a vertical rolling stand is provided by which the two longitudinal edge regions of a cast semifinished product are compressed. However, a reduction in the width of the slab is limited.
Complete removal of the width wedge of ingot cast slabs is often not possible using standard designs of vertical stands, however, since the vertical stands cannot be implemented with sufficient strength. Furthermore, the back-spreading of the material of the slab occurring during the vertical rolling would necessitate an overcompensation of the width wedge. The back-spreading takes place because the width reduction is not distributed evenly over the width, but instead the two longitudinal edge regions of the slab are more severely reformed. So-called dogbones are produced as a result.